From d1232ce72d45ddcabe14f9770a0f8117d8efe74d Mon Sep 17 00:00:00 2001
From: Sarah Vaupel <vaupel.sarah@campus.lmu.de>
Date: Mon, 2 Dec 2019 11:19:50 +0100
Subject: [PATCH] feat(hide-columns): hide empty columns per default

---
 .../src/utils/hide-columns/hide-columns.js    | 30 +++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/frontend/src/utils/hide-columns/hide-columns.js b/frontend/src/utils/hide-columns/hide-columns.js
index 33de28005..f8d2cd755 100644
--- a/frontend/src/utils/hide-columns/hide-columns.js
+++ b/frontend/src/utils/hide-columns/hide-columns.js
@@ -5,6 +5,8 @@ import './hide-columns.scss';
 const HIDE_COLUMNS_CONTAINER_IDENT = 'uw-hide-columns';
 const TABLE_HEADER_IDENT = 'uw-hide-column-header';
 
+const ASYNC_TABLE_IDENT = 'uw-async-table';
+
 const TABLE_UTILS_ATTR = 'table-utils';
 const TABLE_UTILS_CONTAINER_SELECTOR = `[${TABLE_UTILS_ATTR}]`;
 
@@ -158,6 +160,8 @@ export class HideColumns {
   }
 
   updateColumnDisplay(columnIndex, hidden) {
+    let isColumnWithContent = false;
+
     this._element.getElementsByTagName('tr').forEach(row => {
       const cell = row.cells[columnIndex];
       if (cell) {
@@ -165,9 +169,26 @@ export class HideColumns {
           cell.classList.add(CELL_HIDDEN_CLASS);
         } else {
           cell.classList.remove(CELL_HIDDEN_CLASS);
+
+          // determine if this cell has content
+          if (cell.nodeName === 'TD') {
+            let cellHasContent = false;
+            if (this._elementWrapper.hasAttribute(ASYNC_TABLE_IDENT)) {
+              cell.children.forEach(child => {
+                cellHasContent = cellHasContent || !isEmptyElement(child);
+              });
+            } else {
+              cellHasContent = !isEmptyElement(cell);
+            }
+            isColumnWithContent = isColumnWithContent || cellHasContent;
+          }
         }
       }
     });
+
+    if (!hidden && !isColumnWithContent) {
+      this.updateColumnDisplay(columnIndex, true);
+    }
   }
 
   updateHider(hider, hidden) {
@@ -216,3 +237,12 @@ export class HideColumns {
   }
 
 }
+
+function isEmptyElement(element) {
+  for (let child of element.childNodes) {
+    if (child.nodeName !== '#comment')
+      return false;
+  }
+  return true;
+}
+